昆仑山口西8.1级地震前青海省形变及地温前兆特征分析   总被引：6，自引：0，他引：6  

张晓清  顾永康 《高原地震》2002,14(1):70-75

通过对青海省地倾斜、地应力、深井地温3种前兆手段在昆仑山口西8．1级地震前异常的分析与研究，得出了强地震远场前兆的一些初步特征，并与近场前兆异常特征做了比较，这对该省今后强震短期预报将是有益的。  相似文献   

以2000年4月29日河南内乡地震为例谈谈关于计算震级误差的有关问题     

谢智  刘尧兴  谢健健  许孝法  王世昌 《华南地震》2002,22(3):52-57

2000年4月29日河南内乡发生地震，地这次地震，河南地震局台网和中国地震局台网震级量度之间有一定差异。采用不同量规函数和尾波持续时间震级公式计算发现，它们之间所产生的最大差异可达0.5-0.7级。综合分析后认为，2000年4月29日河南内乡地震震级定为ML5.0级较为适宜。  相似文献   

1987年8月2日江西省寻乌MS5.5级地震的震害与烈度分布     

黄莉菁  黄昭  郑师春 《华南地震》2002,22(4):1-8

从寻乌5.5级地震的地震地质构造背景，宏观震害考察结果。结合近场强地面运动观测中几次较大地震的加速度峰值。分析宏观烈度分布特征。认为烈度分布特征除了受构造控制外，还与地形，地基土质条件有关，极震区长轴方向显示鸡笼嶂-寻乌-八尺北西向断裂是寻乌地震的主要发震断层，发震构造受控于华南块体构造应力场，发震区处于北北东向河源-邵武断裂中段和东西向断裂交汇部位。  相似文献   

The El Salvador earthquakes of January and February 2001: context, characteristics and implications for seismic risk     

J. J. Bommer  M. B. Benito  M. Ciudad-Real  A. Lemoine  M. A. Lpez-Menjívar  R. Madariaga  J. Mankelow  P. Mndez de Hasbun  W. Murphy  M. Nieto-Lovo  C. E. Rodríguez-Pineda  H. Rosa 《Soil Dynamics and Earthquake Engineering》2002,22(5)

The small Central American republic of El Salvador has experienced, on average, one destructive earthquake per decade during the last hundred years. The latest events occurred on 13 January and 13 February 2001, with magnitudes M_w 7.7 and 6.6, respectively. The two events, which were of different tectonic origin, follow the patterns of the seismicity of the region although neither event has a known precedent in the earthquake catalogue in terms of size and location. The earthquakes caused damage to thousands of traditionally built houses and triggered hundreds of landslides, which were the main causes of fatalities. The earthquakes have clearly demonstrated trends of increasing seismic risk in El Salvador due to rapid population expansion in areas of high shaking and landslide hazard, exacerbated by deforestation and uncontrolled urbanisation. The institutional mechanisms required for the control of land use and building practice are very weak and present a major obstacle to risk mitigation.  相似文献   

Validation through HVSR measurements of a method for the quick detection of site amplification effects from intensity data: an application to a seismic area in Northern Italy     

Vera D'Amico  Marco Mucciarelli   《Soil Dynamics and Earthquake Engineering》2002,22(6)

An instrumental validation is attempted of an innovative approach devoted to the quick individuation, from macroseismic data, of site amplification phenomena able to significantly modify seismic hazard levels expected on the basis of average propagation effects only. According to this methodology, two evaluations of hazard are performed at each investigated locality: the former, obtained by epicentral intensity data ‘reduced’ at the site through a probabilistic attenuation function and, the latter, computed by integrating such data with seismic effects actually observed at the site during past earthquakes. The comparison, for each locality, between these two hazard estimates allow to orientate the identification of those sites where local amplifications of earthquake ground motion could be significant. In order to check such methodology, indications obtained in this way from macroseismic data are compared with the estimates of transfer functions performed through the HVSR technique applied to microtremors. Results concerning municipalities located in a seismic area of Northern Italy indicate a good agreement between macroseismic and instrumental estimates.  相似文献   

The use of modern statistical theories in the assessment of earthquake hazard, with application to quiet regions of eastern North America     

G. R. Dargahi-Noubary   《Soil Dynamics and Earthquake Engineering》2002,22(5)

It is generally accepted that both deterministic and statistical approaches are useful for the characterization of earthquake hazard. Although the most reliable estimates of seismic hazard can only be based on an improved understanding of the earthquake mechanism, efficient utilization of the appropriate methods provided by recent statistical theories is also important in seismic risk analysis. This is especially true in regions where the connection between seismicity and geologic structure is tenuous at best. We are particularly interested in developing better statistical treatments of data for regions with little known seismic activity. To this end, we have applied three statistical methods to the historical record of seismicity in relatively quiet regions of eastern North America. These are: (1) the threshold method for tail inference, a new theory for modeling earthquakes with sizes above a given threshold, (2) the ‘bootstrap’ technique in which the characteristics of an unknown population are simulated by replacing the true population by an estimated one, and (3) a technique to estimate the number of earthquakes below a given size, in order to compensate for the under-reporting of small earthquakes in most catalogs. A combination of these techniques has been used to estimate the probabilities of future large earthquakes for the regions studied. Because of limitations imposed by existing catalogs, the size estimate used has been maximum intensity.  相似文献   

《CT理论与应用研究》杂志新刊标和地幔速度模型的说明     

《CT理论与应用研究》编辑部 《CT理论与应用研究》2002,11(1):48-51

在《ＣＴ理论与应用研究》杂志１９９４~２００１年本杂志“刊标”的基础上,在其上方增加了象征三维体视学成像的三角形四面体的透视图;该刊标的右下侧为医学断面成像扫描仪(包括各种Ｘ－ＣＴ机与核磁共振ＭＲＩ扫描仪等);其左下侧为三维地幔速度模型和地球核的示意图,切出有两个地幔剖面,表示纵波速度二维变化的剖面。该速度剖面系根据赵大鹏教授的理论和计算方法,按照地球上的两个大圆弧做计算和绘制的彩色图,排在本期封４:第一大圆弧,从北极经西巴基斯坦(２８°Ｎ, ６４°Ｅ)到马尔代夫群岛(３°Ｎ,７３°Ｅ);第二大圆弧从马尔代夫群岛点(３°Ｎ,７３°Ｅ)连接巴布新几内亚之南点(１２°Ｓ,１５０°Ｅ),来计算两剖面速度分布并作图的结果,其具体分布参见封４的两条彩色剖面和相应的地理位置图。由于赵教授这篇论文[１]在中国国内只有很少数图书馆收藏,在Ｅｌｓｅｖｉｅｒ Ｓｃｉｅｎｃｅ的ＥＰＳＬ网站上一般人只能查到摘要,本刊对于该地幔速度模型的制作方法和所用数据资料,该模型的优越性和特征进行了叙述,他所用的地震事件数目,多达７１２８个;用于层析反演成像的震相到时数多到近一百万条。该速度如下的特点:在所采用的速度结构中,包含用几个复杂形状的地质速度界面,如莫霍面,以及下沉板块的分界  相似文献   

Ground truth seismic events and location capability at Degelen mountain, Kazakhstan     

Chad Trabant  Clifford Thurber  William Leith 《Physics of the Earth and Planetary Interiors》2002,131(2):155-171

We utilized nuclear explosions from the Degelen Mountain sub-region of the Semipalatinsk Test Site (STS), Kazakhstan, to assess seismic location capability directly. Excellent ground truth information for these events was either known or was estimated from maps of the Degelen Mountain adit complex. Origin times were refined for events for which absolute origin time information was unknown using catalog arrival times, our ground truth location estimates, and a time baseline provided by fixing known origin times during a joint hypocenter determination (JHD). Precise arrival time picks were determined using a waveform cross-correlation process applied to the available digital data. These data were used in a JHD analysis. We found that very accurate locations were possible when high precision, waveform cross-correlation arrival times were combined with JHD. Relocation with our full digital data set resulted in a mean mislocation of 2 km and a mean 95% confidence ellipse (CE) area of 6.6 km² (90% CE: 5.1 km²), however, only 5 of the 18 computed error ellipses actually covered the associated ground truth location estimate. To test a more realistic nuclear test monitoring scenario, we applied our JHD analysis to a set of seven events (one fixed) using data only from seismic stations within 40° epicentral distance. Relocation with these data resulted in a mean mislocation of 7.4 km, with four of the 95% error ellipses covering less than 570 km² (90% CE: 438 km²), and the other two covering 1730 and 8869 km² (90% CE: 1331 and 6822 km²). Location uncertainties calculated using JHD often underestimated the true error, but a circular region with a radius equal to the mislocation covered less than 1000 km² for all events having more than three observations.  相似文献   

Most likely locations of large earthquakes in the Kanto and Tokai areas, Japan, based on the local recurrence times     

Max Wyss  Shozo Matsumura 《Physics of the Earth and Planetary Interiors》2002,131(2):173-184

We examined the hypothesis that minima in local recurrence time, T_L, or equivalently maxima in local probability, P_L, may map asperities in the Kanto and Tokai areas of Japan, where the earthquake catalog of the National Research Institute for Earth Science and Disaster Prevention (NIED) is complete at the M=1.5 (M1.5) level. We mapped T_L (P_L) based on the a- and b-values of the nearest earthquakes within 20 km of every node of a grid spaced 0.01° for M7 target events. Only earthquakes within the top 33 km were used. The b-values increase strongly with depth, in several areas. Therefore, some of the T_L (P_L) anomalies are not revealed if data from the entire crustal seismogenic zone are mixed. Thus, we mapped T_L (P_L) separately for the top 15 km and the rest of the depth range, as well as for the entire seismogenic crust. The resulting T_L- and P_L-maps show that approximately 12% of the total area shows anomalously short recurrence times. Out of six shallow target events with M≥6.5 and which occurred since 1890, five are located within the anomalous areas with T_L <450 years. We interpret this to mean that areas with anomalously short T_L map asperities, which are more likely than other areas to generate future target events. The probability that this result is due to chance is vanishingly small. The great Kanto rupture of 1923 appears to have initiated in the most significant asperity we mapped in the study area. One anomaly is located in the northeastern part of the area of the proposed future rupture of the Tokai earthquake, and another one at its southwestern corner. The absolute values of T_L calculated are uncertain because they depend on the size of the volume used for the calculation.  相似文献   

辽宁省地震前兆台网技术改造概述     

卢群  殷为民  刘淑芹  秦家林  金众范 《东北地震研究》2002,18(3):7-13

“九五”期间实施的《辽宁省地震前兆台网技术改造项目》使辽宁省地震前兆观测技术系统由模拟到数字实现了质的飞跃，本文对项目的技术思路，实施情况，取得的成果及建设特色进行了介绍。  相似文献